Update OnClose in wxpython examples to use the same logic as in wx.chromectrl

[GoogleCodeExporter]

In the wxpython examples in the OnClose event there are calls to CloseBrowser() 
and Destroy() window. In some complex wx app it turned that this was the cause 
of crashes when closing multiple browser tabs. The solution is to only call 
ParentWindowWillClose() in the OnClose event - this behavior was already 
updated in wx.chromectrl.

Original issue reported on code.google.com by czarek.t...@gmail.com on 12 Jan 2014 at 5:35